GB1207369A - Electrodes for storage batteries and electrode plaques therefor - Google Patents

Abstract

1,207,369. Accumulator electrodes. PORTABLE POWER CORP. 20 Dec., 1967 [27 Dec., 1966; 7 April, 1967; 15 Aug., 1967], No. 57796/67. Heading H1B. [Also in Division C7] A secondary battery electrode is prepared by (a) impregnating a porous electrically conductive matrix with an aqueous solution of a metal salt end (b) treating the impregnated matrix with an aqueous solution of a carbonate, bicarbonate or sulphite to form a water-insoluble salt of the metal. The matrix may be of sintered nickel. The metal salt solution may be a hot saturated solution of nickel nitrate or cadmium nitrate containing at least 25 gm. ions/ litre of the metal ion. The matrix may be impregnated by immersing it in the solution under vacuum and draining it. The metal salt may be converted to insoluble metal carbonate by treatment with potassium carbonate solution, the matrix being afterwards dried by draining or by heating and/or dessication. Any remaining nitrate may then be reduced by treatment with a compound such as ascorbic acid which contains a -C(OH) = C(OH)- group. The metal carbonate may then be converted to the metal oxide by thermal decomposition at 600-750‹ F. for Ni or 850- 875‹ F. for Cd and this in turn may be converted to Ni 2 O 3 or Cd metal by electrolytic oxidation or reduction respectively at a voltage of at least 1À4 and a current density of at least 0À1 amps/ sq. in. In an alternative procedure the nickel nitrate may be converted to Ni 2 O 3 in two stages by electrolysis in K 2 CO 3 solution at 2-5 volts and a current density of 0À5-2 amps/sq. in. followed by electrolysis in KOH solution at 1À3-5 volts and a current density of 0À05-0À5 amps/sq. in. In a second alternative procedure the Ni(NO 3 ) 2 is chemically converted to NiCO 3 which is then converted directly to Ni 2 O 3 by electrolysis in KOH solution at 2-5 volts and a current density of 0À5-2 amps /sq. in. Finally (Example 7) the electrode may be compressed before use. In Example 3 and 4, Ni and Cd electrodes according to the invention are used in a polyethylene accumulator having paper separators and aqueous KOH electrolyte. In Example 4 there are more Ni electrodes than Cd electrodes.